DESCRIPTION (from the application): The Biostatistics Core provides the personnel, expertise, and computational resources needed for maximum utilization of the data collected by the investigators in the Program Project. It is responsible for oversight, quality control, and integration of statistical modeling, data preparation, and data analysis across all projects. The aims of the Core are to integrate statistical modeling and data sources across projects, to provide biostatistical support for experimental design and modeling matched to the hypotheses under investigation in each of the projects, to provide computational support for data analysis, and to provide central data management services. The Core will have responsibility for monitoring the progress of data collection and analysis in each of the projects. It will advise each project leader on data quality issues. It will construct program-wide data sets in a common format on a regular schedule. These data sets will form the basis for an integrated library of data that can be used to test the inter-related hypotheses described in the project overview. The Core will be responsible for providing statistical consulting services to each project, including advice on use of statistical software. When data sets or analysis software developed under this project are to be made publicly available, the Core will be responsible for preparing the necessary computer files and documentation. The Core's responsibility includes recommending and maintaining statistical software, providing expertise on data conversion between different software packages as needed, and conducting the statistical data analyses required for studies involving multiple projects. The Core is responsible for assisting individual projects in creating summary data sets for high-level (cross-project) analysis, for maintaining a program-wide archive of these data sets, and for collecting and updating these data sets on a regular Basis (-at least three times per year). The. Biostatistics Core will coordinate with and serve as the agent for the Administrative Core in preserving copies of Program Project data sets.